The present invention relates to in vivo plasmapheresis as described in U.S. Pat. Nos. 4,950,224 and 5,735,809. More particularly, the present invention relates to methods and apparatus for the continuous utilization and/or treatment of the in vivo extracted plasma in ex vivo or implanted devices, fermentors, bioreactors, and other mechanisms developed and used in the fields of tissue engineering, cellular therapy, artificial organs, and the like.
Many diseases and disorders result from disruption of cellular function or destruction of tissues and of the body. Physicians treat tissue loss or organ failure with drug therapy, organ transplantation, surgical reconstruction, or mechanical devices. However, drug therapy is usually expensive, not always effective, and many patients suffer from serious side effects, suitable transplantable tissue and organs are in short supply, often with immune rejection, and current mechanical devices cannot perform all the functions of a single organ. Thus, there is a need for improved treatments for these diseases and disorders.
All of the aforesaid fields of science use bioreactors and other such mechanisms used in biotechnology as well as drugs or chemical processes used in plasma protein manipulations and the subsequent return of the modified plasma to the body to treat, modify, or reconstitute specific physiological functions. These applications are emerging sciences that use in vivo and ex vivo cell cultures and cell-secreted protein products to reconstitute body parts, tissues, and organs, in functional artificial organs (such as the pancreas and liver), and in specialized fermenters, and continuous cultures to create or modify immune system components and constructs for treatment of specific disease states. Such devices and bioreactors are also useful for the expansion of cell cultures and their subsequent harvesting and re-transplantation in patients whose immune system and stem cell population has been decimated by chemical and radiation therapy. Such devices and bioreactors are also useful to act as the access mechanism and transport vehicle for monitoring and effecting drug or gene therapy that may be difficult or cannot be performed in vivo because of the toxicity or trauma of the process. In the case of artificial organs, autologous, xenogenic, and allogenic cells and tissues as well as substitute materials and mechanisms may be used to perform the functions of the organ implanted or ex vivo and remote from the physiological site of the original organ in an artificial construct. These ex vivo devices can also be used to isolate, separate, and harvest and/or modify specific human immune system proteins, that reside in the plasma, by means of series cascade filtration, or by means of selective ligand attachments to hollow fibers or other substrates in the plasma flow stream.
Cell culture bioreactors are systems which have one or more of the following purposes: (a) the expansion (replication) of specific human cells and/or tissue complexes to be used for therapeutic re-implantation, (b) the expression (production) of cells and/or cellular products (antibodies, cytokines, proteins, immune system complexes, etc.) to be used in the therapy of specific disease states, (c) the utilization of such cellular cultures and cell populations which mimic the performance of in vivo tissue to perform in substitution or in supportive augmentation of the functions of organs (i.e., pancreas, liver) and other specialized tissues (i.e., cartilage), and (d) to act as vehicles for the modification of cells by gene therapy techniques. In the case of artificial organs, such cellular activity may be augmented, supported, controlled, or replaced by alternate electromechanical or chemical system constructs providing specialized functions such as respiration, separation, filtration, sensor transduction, signal conditioning, computation, and system control effectors.
An example of both (a) and (b) purposes occurs in cancer therapy where hyper-intensive chemotherapy is used for efficient destruction of the oncocellular tissue and which also destroys the bone marrow and circulating stem cells responsible for the genesis of the human immune system. Treatment protocol in this case is to stimulate and harvest bone marrow and/or peripheral circulating stem cells and place them in cryo-storage, or a bioreactor, prior to and pending completion of the chemotherapy. The harvested stem cells are re-implanted, and in time regenerate the immune system and re-populate the patient""s stem cell structure.
A bioreactor may be of any class, size or have any one or number of desired features, depending on the product to be achieved. Different types of bioreactors include tank bioreactors, immobilized cell bioreactors, hollow fiber and membrane bioreactors as well as digesters. There are three classes of immobilized bioreactors, which allow cells to be grown: membrane bioreactors, filter or mesh bioreactors, and carrier particle systems. Membrane bioreactors grow the cells on or behind a permeable membrane, allowing the nutrients to leave the cell, while preventing the cells from escaping. Filter or mesh bioreactors grow the cells on an open mesh of an inert material, allowing the culture medium to flow past, while preventing the cells from escaping. Carrier particle systems grow the cells on something very small, such as small nylon or gelatin beads. The bioreactor can be a fluidized bed or a solid bed. Other types of bioreactors include pond reactors and tower fermentors.
Different bioreactors utilize different components for mixing the contents including the use of stirring paddles, turbines, deep jet fermentors, gas inflow, etc. Bioreactor control may be achieved by any desired purpose, including biomass sensors and real-time off-line sensors. Bioreactors may also be classified according to how they keep contaminants excluded.
Presently, all apparatus, systems and methods utilize blood or plasma and/or serum media separated from blood of the patient of an allogenic or xenogenic donor by ex vivo means such as centrifugation or ultrafiltration. Blood contains erythrocytes, platelets or other large molecular weight blood components which will coagulate or clot in the ex vivo components causing disruption if not inoperability of the systems. Centrifugation or ultrafiltration requires purchase and operation of additional apparatus, thereby substantially increasing the cost of the procedure and are bulky and thus immobilizes the patient. Centrifugation also requires a significant amount of blood, placing an unacceptable burden on the patient or allogenic donor. Moreover, the processing of whole blood substantially increases the incidence of infection or contamination of the blood cells, and ultimately the patient as well as the incidence of damage to the red and white blood cells.
Some proposed bioreactor systems utilize whole blood removed from the patient or donor and separate the plasma into the blood from the blood cells ex vivo. Such plasmapheresis systems do not obviate the disadvantages discussed above since whole blood still must be removed from the source and filtered to separate the plasma to be directed to the bioreactor. It is to the elimination of the aforesaid disadvantages that the present invention is directed.
The present invention is directed to a method of continuously providing cell culture media to cells, tissues or organ constructs in bioreactors, tissue engineering devices, artificial organs, and other cell culture devices using in vivo plasma separation by implanting a plasma separation filter device within a blood vessel of a patient, or donor separating blood plasma from whole blood in vivo, directing the plasma from the plasma separation filter device to a bioreactor or other cell culture device, and exposing the plasma to cells, tissue or an organ within the bioreactor or other cell culture device directly or indirectly through a membrane immune system barrier. Expressed or replicated cells, tissue segments, other cell culture products are recovered or harvested and may be directed to a selected delivery system where cell products, cells or tissues may be directed to specific patient sites or implanted in the patient. Alternatively, the culture product may be returned to the patient""s blood. The spent cell culture media (plasma) may be discarded or returned to the patient or donor blood where it can be revitalized and reconstituted by the donors organs (i.e. kidneys or liver) for reuse in the bioreactor device on a continuous basis. The invention includes apparatus for carrying out the aforesaid method.